fix invalid input tag attrs

index.html

@@ -89,8 +89,7 @@ footer a:hover {
 
 <p>
     dices
-    <input type="text" id="dice_num" align="middle"
-        type="number" min="1" size="2" value="6">
+    <input id="dice_num" type="number" min="1" size="2" value="6">
     <input type="button" onclick="decrement()" value="-">
     <input type="button" onclick="increment()" value="+">
     <input type="button" onclick="roll()" value="roll">